As greater amounts of information continue to be stored on, and accessed by, computerized information services, mechanisms which enable a user to locate and review information of interest become a critical component of an information retrieval system. Typically, one of two different types of mechanisms is employed by users to access documents that are relevant to their needs or interests. One such mechanism is the hierarchal browser, which permits the user to view groups of documents and identify the documents within the context in which they are stored. If a document of interest is located, related documents can be easily found as well, because the user is provided with the ability to look in areas surrounding the document of interest to see other documents that are stored with it. Hierarchal browsers are essentially one dimensional, in that a single tree-like structure is provided for navigating among documents. This mechanism may be acceptable for single-user systems, in which the user authored the hierarchy. However, in multi-user systems, such as news databases, help lines, work group databases, and the like, not all users may find the single hierarchy to be cognitively intuitive, and therefore may have difficulty navigating through the hierarchy to find documents of interest.
The other type of retrieval mechanism, namely a full-text search engine, permits users to enter queries, and respond to those queries by returning document titles. These titles may be accompanied by relevance rankings or other indicators of the degree to which each document corresponds to the query. The document titles are typically presented to the user in the form of a list that may be sorted by relevance rankings, and do not provide any information regarding the context of the documents in the full database of information. Furthermore, they do not give the user the ability to browse through the spaces that are occupied by the listed documents, to locate related documents which were not selected as a result of the query. Such systems tend to work best for users who are looking for specific information, and they require a certain level of skill in constructing appropriate queries, since the results are highly dependent upon the terms which the user employs as an expression of interest.
It is an objective of the present invention to provide a document retrieval mechanism that offers the functionality of a full-text search engine, to enable a user to readily identify documents meeting that user's criteria, while at the same time offering the flexibility of a browser, to permit the user to locate related documents that may not match a specific query but which may nevertheless be of interest to the user.